/Engine/Plugins/EnhancedInput/Source/EnhancedInput/Public/UserSettings/EnhancedInputUserSettings.h
Returns the number of keys for the given mapping name
[UFUNCTION](Programming/UnrealArchitecture/Reference/Functions)(BlueprintCallable, Category="Enhanced Input|User Settings", Meta=(ReturnDisplayName="Number of keys")) virtual int32 GetMappedKeysInRow ( const [FName](API\Runtime\Core\UObject\FName) MappingName, [TArray](API\Runtime\Core\Containers\TArray)< [FKey](API\Runtime\InputCore\FKey) > & OutKeys ) const